Energy harvesting, also known as power harvesting or energy scavenging, is the process by which energy is derived from external sources (e.g., solar power, thermal energy, wind energy, salinity gradients, and kinetic energy), captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks. Energy harvesters convert ambient energy into electrical energy and provide a very small amount of power for low-energy electronics. Thus, the power consumption of the electronics needs to be as low as possible. A common way of decreasing the power consumption of electronics, in particular digital, i.e., logic circuitry such as all kinds of gates and inverters, is to decrease the supply voltage. The minimum supply voltage of a logic circuit is dependent on various manufacturing process parameters. The trigger levels of logic circuits are dependent on the (minimum) supply voltage and also on the manufacturing process parameters, meaning that the reliability of logic circuits at lower supply voltages is low or that power consumption is high when the supply voltage is increased in order to increase the reliability of the logic circuit. Thus, there is a need for reliable logic circuits at low voltages.